Cook County Medical Examiner Dr. Stephen Cina said Friday that tests on the remains of Urooj Khan did not detect cyanide in tissues or what remains of his digestive system.

But, as the Chicago Sun-Times reports, Cina said "cyanide has a short half-life and may be lost over the postmortem period unless tissue are adequately preserved." So, it's not entirely surprising that none was found in the remains.

The medical examiner's office initially ruled that the 46-year-old Khan had died of natural causes. No autopsy was performed. At that time, the medical examiner's office did not routinely do autopsies on those older than 45 unless the death was suspicious. The age cutoff has since been raised to 50.

A few days after that initial ruling, though, a family member contacted the medical examiner's office and expressed concern about Khan's death. That led to tests on some of Khan's blood that had been stored. A lethal amount of cyanide was discovered.